Biology MCQ on Molecular Biology:- Explanation: Proteins are made up of b) R2 and R3, R1 and R4

1. What is Molecular Biology? hundreds or thousands of smaller units c) R1 and R3, R2 and R4
a) Deals with the physical structures and known as amino acids that are linked in d) R2 and R1, R3 and R4
processes of biological events lengthy chains. A protein is made up of
b) Deals with the chemical structures 20 different types of amino acids that Answer: b
and processes of chemical events can be combined in various ways. Explanation: For recombination to
c) Deals with the physical structures and 5. Which of the following is RNA made occur, the R2 segment of the Trp DNA
processes of chemical events up of? molecule must recombine with R3
d) Deals with the chemical structures a) Adenine, Cytosine, Guanine, and segment of the bottom DNA molecule.
and processes of biological events Uracil R1 segment of the top molecule must
b) Adenine, Guanine, Cytosine, and recombine with R4 segment of the
Answer: d Thymine bottom DNA molecule.
Explanation: Molecular biology is a c) Adenine, Guanine, Uracil, and 9. What is the resolution?
branch of biology that studies the Thymine a) Exchange of DNA fragments
chemical structures and processes of d) Adenine, Uracil, Cytosine, and b) Heterochromatin structure formation
biological events involving molecules, Thymine c) Regeneration of duplex DNA
the basic units of life. The study of molecule
molecular biology is concerned with Answer: d d) Cleavage of holiday junction
nucleic acids (such as DNA and RNA) Explanation: Ribonucleic acid (RNA) is
and proteins—macromolecules. a linear molecule made up of four Answer: c
2. Which of the following is DNA made different ribonucleotide bases: adenine Explanation: In the process of
up of? (A), cytosine (C), guanine (G), and homologous recombination, DNA
a) Adenine – Guanine uracil (U). molecules are regenerated by the process
b) Cytosine – Thymine advertisement of genetic exchange. This is known as
c) Both Adenine – Guanine & Cytosine 6. Which of the following is a type of the process of resolution.
– Thymine RNA involved in protein synthesis? 10. Which two Uvr component
d) None of the mentioned a) snRNA molecules scan the DNA during
b) rRNA nucleotide excision repair?
Answer: c c) yRNA a) UvrB, UvrC
Explanation: DNA is a linear molecule d) dsRNA b) UvrC, UvrA
made up of four different types of c) UvrD, UvrA
nucleotide bases: adenine (A), cytosine Answer: b d) UvrA, UvrB
(C), guanine (G), and thymine (T) (T). Explanation: Protein synthesis requires
The DNA sequence is the order in which three different forms of RNA. Answer: d
these bases appear. Messenger RNA (mRNA), transfer RNA Explanation: In nucleotide excision
3. Who is known as the father of (tRNA), and ribosomal RNA are the repair complex of two UvrA and UvrB
Molecular biology? three types of RNA (rRNA). molecules scan the DNA with two UvrA
a) Linus Carl Pauling 7. How many unusual bases are subunits being responsible for detecting
b) James Watson observed in a tRNA molecule? the distortions to the helix. Upon
c) Francis H. Crick a) 1 encountering a distortion, UvrA exits the
d) Mahlon B. Hoagland b) 3 complex and create a single stranded
c) 5 bubble with UvrB.
Answer: a d) 0 11. In the following type of libraries pick
Explanation: Pauling was called the the odd one out.
“Father of Molecular Biology” by Answer: c a) cDNA library
Francis Crick. His discovery of sickle Explanation: Five unusual bases, b) A DNA library
cell anaemia as a “molecular illness” produced by enzymatic modification of c) Z DNA library
paved the path for molecular analysis of the usual bases, may be observed in a d) B DNA library
genetically acquired alterations. tRNA molecule. These are
4. Proteins are made up of which of the pseudouridine, dihyrdouridine, Answer: a
following? hypoxanthine, thymine and Explanation: cDNA library lacks DNA
a) Nucleic acids methylguanine. Of these five, unusual fragments from the genomic DNA. This
b) Amino acids bases pseudouridine and dihyrdouridine type of library is produced by the action
c) Nuclease are most commonly found in the tRNA of reverse transcriptase on the mRNA
d) None of the mentioned molecules. molecule to synthesize complementary
8. What is the correct pair of the four DNA molecules without the intervening
Answer: b segments (R1, R2, R3, and R4)? introns.
a) R1 and R2, R3 and R4
12. Which of the following parts of the Explanation: Ethidium bromide only 19. Which of the following does not take
mRNA determines the specificity of the helps in tagging the DNA molecules to part in gene expression?
amino acid attached? make the visible under the UV radiation a) Transcription
a) Acceptor stem due to its fluorescence property, but does b) RNA processing
b) D loop not take any part in the separation of c) Replication
c) ΨU loop DNA molecules during electrophoresis. d) Translation
d) Variable loop 16. Which of the following is the slowest
process among the following? Answer: c
Answer: a a) Splicing Explanation: Replication is the coping of
Explanation: Genetic, biochemical and b) Translation the gene in double but plays no role in
X-ray crystallographic evidence indicate c) Transcription the production of protein thus,
that the specificity determinants are d) Replication expression of gene. Transcription is the
clustered at the two distant sites on the production of RNA from DNA and RNA
molecule. They are the acceptor stem Answer: b processing is used for stabilizing the
and the anticodon loop. Explanation: The speed of DNA RNA in cytosol ad excision of non-
13. Which of the following is not true replication that is, 200 to 1000 coding regions. Translation is the major
about nucleotides? nucleotides per second. Translation takes process that leads to the formation of
a) Energy rich molecules place at a rate of only 2 to 20 amino polypeptide chain.
b) Monomeric units acids per second. 20. Which of the following is a character
c) Ubiquitous substances 17. Which of the following function of of ORF?
d) Non enzymatic molecules DNA is necessary for the purpose of a) Non – overlapping
evolution? b) 3 – nucleotide codons
Answer: d a) Mutation c) Contiguous
Explanation: The nucleotides are known b) Replication d) Intron
to be enzymatic molecules. For example, c) Translation
ribozymes are catalytic molecules. Also d) Transcription Answer: d
certain derivatives of nucleotides such as Explanation: Exons are the part of
ATP, coenzyme A, nicotinamide adenine Answer: a nascent RNA that are connected together
dinucleotide, etc., are important catalytic Explanation: Mutation facilitates the to form RNA after the removal of
molecules that participate in various change of bases within a DNA and if this introns by the splicosome. The
enzymatic processes. change encodes for a viable amino acid splicosome in the complex formed in the
14. Which of the following is wrongly which in turn may lead to the synthesis nucleus with nascent RNA being the
paired? of a different protein. This protein exerts substrate for the formation of mature
a) Nucleic acid – hydrogen bond a phenotypic character to the organism RNA after its splicing and other post
b) Polysaccharide – glycosidic bond which may be different from the wild transcriptional mechanisms.
c) Proteins – peptide bond type character or may generate a unique 21. Which of the following does not
d) Phospholipids –phosphate linkage character itself, thus leading to contribute to the stability of tRNA?
evolution. a) Hydrogen bonding
Answer: a 18. Which of the following is not a b) Hydrophobic interactions
Explanation: Nucleic acids, that is, DNA component of the nucleic acid c) Base and sugar-phosphate backbone
and RNA show phosphodiesterase backbone? interaction
linkage which is the major type of a) Nucleotide d) Base pairing
linkage. Without the phosphodiester b) Phosphate group
bonds between the phosphate and c) Pentose sugar Answer: b
adjacent 3’OH sugar molecule the d) Phosphodiesterase bond Explanation: Due to the negative charge
backbone will not be formed. Therefore, of the tRNA backbone, it is unlikely for
the nucleotides would not be able to Answer: a the molecule to have a hydrophobic
attach and bond to form a nucleic acid. Explanation: A nucleic acid backbone is nature. Thus, hydrophobic interactions
15. Which of the following factors do mainly composed of a pentose- do not play any role in the structural
not provide to the separation of DNA phosphate unit which acts as a monomer. stability of the molecule. On the other
fragments during electrophoresis? The repeat of this monomer is attached hand, the other interactions such as the
a) Size together by the phosphodiesterase hydrogen bonding lead to base pairing
b) Matrix density linkage, thus, giving rise to the which leads to its classic clover leaf
c) Chargaff’s rule backbone. The nucleotides attached to model.
d) Ethidium bromide the sugar moieties forms the side chain 22. Which histone molecule produces
which gives rise to the hydrogen linkage novel binding sites for protein
Answer: d with its complementary strand. components of the kinetochore?
a) H3
b) H4 TAACGTTA. Thus, when the first is 29. During DNA cloning which of the
c) H2A read from left to right and the later read following is not a crucial requirement?
d) CENP – A from right to left the sequence of the a) Protein expression
bases is exactly the same. This is the b) Vector
Answer: d criteria for a sequence to be palindromic. c) Molecular cutter
Explanation: A histone variant CENP – 26. Which of the following cannot be d) DNA inserts
A, is associated with the nucleosome used for the separation of nucleic acids?
that include centromeric DNA. In this a) Northern blotting Answer: a
region CENP – A replaces H3 subunit in b) PAGE Explanation: DNA cloning typically
the nucleosomes. These nucleosomes are c) SDS – PAGE involves a vector that carried the DNA
incorporated into the kinetochore which d) None of the mentioned insert into a host cell. Molecular cutters
mediates attachment of the chromosome are important to incorporate the DNA
to the mitotic spindle. The extended tail Answer: c insert into the vector thus giving rise to
of CENP – A may generate these novel Explanation: Sodium dodecyl sulphate is the chimera molecule. Hence cloning is
binding sites for other binding protein a detergent, often used in biochemical complete if the organism replicates and
components of the kinetochore. preparations, binds to proteins and the DNA insert replicates along with it.
23. Which of the following is not causes them to form a rod like structure. 30. Which of the following is not
promoted by histone tail modification? Most proteins bind SDS in the same required for DNA sequencing?
a) Nucleosome sliding ratio (1.4g per g of protein). Thus, the a) Polymerase chain reaction
b) Nucleosome remodeling electrophoresis of proteins in an SDS – b) Electrophoresis
c) Gene expression containing polyacrylamide gel separates c) Restriction digestion
d) Formation of repressive structures them in order of their molecular masses. d) Cloning
It is not known to have a similar effect
Answer: a on nucleic acids. Answer: d
Explanation: Nucleosome sliding is a 27. Which of the following organism has Explanation: DNA sequencing is the
type of Nucleosome remodeling. It is been found to have a positively process of determining the precise order
facilitated by Nucleosome remodeling supercoiled DNA? of nucleotides within a DNA molecule.
complex. It cannot be promoted alone by a) Thermus aquaticus It includes the methods and technologies
modifying histone tail unless a b) Saurida tumbil of restriction endonuclease,
nucleosome remodeling complex comes c) Monarda didyma electrophoretic techniques and
along. d) Cyanobacteria Polymerase Chain Reaction.
24. Which of these factors contribute to 31. Though unusual, pre – tRNA also
a decrease in gene density? Answer: a undergo splicing. Which of the
a) Intergenic sequence Explanation: The only organisms that following helps in achieving this?
b) Cell size are found to have positively supercoiled a) tRNA itself
c) Operon DNA are certain thermophiles, b) Endonuclease
d) Exon sequence microorganisms living under conditions c) Splicosome
of extremely high temperature. Example d) RNA polymerase exonuclease activity
Answer: a of one such bacteria found in hot springs
Explanation: As the genome size are Thermus aquaticus. Answer: b
increases the DNA between two 28. Which of the following does not Explanation: Though unusual, pre –
consecutive sequences increase, known occur during cell division in tRNA and pre – rRNAs also undergo
as the Intergenic sequences. Thus, with prokaryotes? splicing. In contrast to other splicing
the increase in genome complexity, a) DNA rejoining reactions, which involve the activity of
regulatory sequences are required for the b) Strand passage catalytic RNAs, tRNA splicing is
proper functioning of the different c) Multiple decatenations mediated by conventional protein
mechanisms. These regulatory sequences d) DNA cleavage enzymes. An endonuclease cleaves the
are stored in these Intergenic sequences. pre – tRNA at the splice site to excise
25. Which of the following will form a Answer: c the intron, followed by the joining of the
palindromic sequence? Explanation: Between the steps of DNA exons to form a mature tRNA molecule.
a) AGTCCTGA cleavage and DNA rejoining, the
b) GTTCCAAG topoisomerase promotes the passage of a
c) ATTGCAAT second segment of DNA through the
d) GTTGGAAC break. Topoisomerase function thus
involves DNA cleavage, strand passage
Answer: c and DNA rejoining in highly
Explanation: The complementary coordinated manner.
sequence of ATTGCAAT is